Prevalence of cefixime-resistant Neisseria gonorrhoeae in Melbourne, Australia, 2021-2022.

While ceftriaxone remains the first-line treatment for gonorrhoea, the US CDC recommended cefixime as a second-line treatment in 2021. We tested 1176 Neisseria gonorrhoeae isolates among clients attending the Melbourne Sexual Health Centre in 2021-2022. The prevalence of cefixime resistance was 6.3% (74/1176), azithromycin resistance was 4.9% (58/1176) and ceftriaxone resistance was 0% (0/1176). Cefixime resistance was the highest among women (16.4%, 10/61), followed by men-who-have-sex-with-women (6.4%, 7/109), and men-who-have-sex-with-men (5.8%, 57/982). The prevalence of cefixime-resistant N. gonorrhoeae exceeds the threshold of the 5% resistance level recommended by the World Health Organization; and thus, cefixime treatment would have limited benefits in Australia.

Systematic review and meta-analysis of the association between Mycoplasma genitalium and Pelvic inflammatory disease (PID).

BACKGROUND: Differences in opinion concerning the contribution of M. genitalium to pelvic inflammatory disease (PID) has resulted in inconsistencies across global testing and treatment guidelines. We conducted a systematic review and meta-analysis to determine the association between M. genitalium and PID and M. genitalium positivity within PID cases to provide a contemporary evidence base to inform clinical practice (PROSPERO registration: CRD42022382156). METHODS: PubMed, Embase, Medline and Web of Science were searched to Dec 1, 2023 for studies that assessed women for PID using established clinical criteria and used nucleic acid amplification tests to detect M. genitalium. We calculated summary estimates of the 1) association of M. genitalium with PID (pooled odds ratio [OR]) and 2) proportion of PID cases with M. genitalium detected (pooled M. genitalium positivity in PID), using random-effects meta-analyses, with 95% confidence intervals (CI). RESULTS: Nineteen studies were included: 10 estimated M. genitalium association with PID, and 19 estimated M. genitalium positivity in PID. M. genitalium infection was significantly associated with PID (pooled OR=1.67 [95%CI: 1.24-2.24]). The pooled positivity of M. genitalium in PID was 10.3% [95%CI: 5.63-15.99]. Subgroup and meta-regression analyses showed that M. genitalium positivity in PID was highest in the Americas, in studies conducted in both inpatient and outpatient clinic settings, and in populations at high risk of sexually transmitted infections. CONCLUSIONS: M. genitalium was associated with a 67% increase in odds of PID and was detected in about one in ten clinical diagnoses of PID. These data support testing women for M. genitalium at initial PID diagnosis.

Azithromycin or Doxycycline for Asymptomatic Rectal Chlamydia trachomatis.

BACKGROUND: Rectal chlamydia is a common bacterial sexually transmissible infection among men who have sex with men. Data from randomized, controlled trials are needed to guide treatment. METHODS: In this double-blind trial conducted at five sexual health clinics in Australia, we randomly assigned men who have sex with men and who had asymptomatic rectal chlamydia to receive doxycycline (100 mg twice daily for 7 days) or azithromycin (1-g single dose). Asymptomatic chlamydia was selected as the trial focus because more than 85% of men with rectal chlamydia infection are asymptomatic, and clinical guidelines recommend a longer treatment course for symptomatic infection. The primary outcome was a negative nucleic acid amplification test for rectal chlamydia (microbiologic cure) at 4 weeks. RESULTS: From August 2016 through August 2019, we enrolled 625 men (314 in the doxycycline group and 311 in the azithromycin group). Primary outcome data were available for 290 men (92.4%) in the doxycycline group and 297 (95.5%) in the azithromycin group. In the modified intention-to-treat population, a microbiologic cure occurred in 281 of 290 men (96.9%; 95% confidence interval [CI], 94.9 to 98.9) in the doxycycline group and in 227 of 297 (76.4%; 95% CI, 73.8 to 79.1) in the azithromycin group, for an adjusted risk difference of 19.9 percentage points (95% CI, 14.6 to 25.3; P<0.001). Adverse events that included nausea, diarrhea, and vomiting were reported in 98 men (33.8%) in the doxycycline group and in 134 (45.1%) in the azithromycin group (risk difference, -11.3 percentage points; 95% CI, -19.5 to -3.2). CONCLUSIONS: A 7-day course of doxycycline was superior to single-dose azithromycin in the treatment of rectal chlamydia infection among men who have sex with men. (Funded by the National Health and Medical Research Council; RTS Australian New Zealand Clinical Trials Registry number, ACTRN12614001125617.).

Bacterial vaginosis after menopause: factors associated and women's experiences: a cross-sectional study of Australian postmenopausal women.

Background Bacterial vaginosis (BV) is the most common cause of vaginal discharge in reproductive age women; however, little is known about it after menopause. We aimed to learn more about BV in Australian postmenopausal women. Methods We conducted an online survey (July-September 2021). Participants were recruited via social media and professional networks and asked about demographic characteristics, sexual history and BV experiences. Outcomes of interest were the proportion who had heard of BV, had BV ever, or had BV after menopause. Factors associated with these outcomes were assessed using logistic regression. Results Of 906 participants, 83% were included in the analysis. Overall, 37.9% had heard of BV, 11.0% reported having a BV diagnosis ever, 6.3% reported having a BV diagnosis after menopause and 4.4% reported having a BV diagnosis only after menopause. Multivariable analysis found that among all women the odds of having a BV diagnosis after menopause were increased for those who had BV before menopause, had douched in the past 12months, or had a previous STI diagnosis. Among those in a sexual relationship, a BV diagnosis after menopause was associated with a BV diagnosis before menopause, or being in a sexual relationship of 5years or less in duration. About half who reported BV after menopause described recurrences, distress, and a detrimental effect on sexual relationships. Conclusions BV in postmenopausal women is associated with sexual activity, and impacts negatively on their lives. Research into BV should not be limited to reproductive age women.

Management of acute sexual assault presenting to a large Australian sexual health clinic in 2012-2021: a retrospective clinical audit.

Background The incidence of sexual assault continues to rise in Australia. This study aimed to describe the nature of assault, HIV/STI positivity, and its management at a sexual health clinic. Methods We performed a chart review of 516 sexual assault cases presenting to Melbourne Sexual Health Centre between 2012 and 2021, collecting data on victim demographics, details of assault, HIV/STI testing and positivity, police involvement, and offer of counselling. Results We included 516 cases: 124 males (24.0%); 384 females (74.4%); and eight transgender (1.6%) victims. The proportion of assault cases presenting to Melbourne Sexual Health Centre increased from 0.1% (37/37,070) in 2012 to 0.2% (56/36,514) in 2021 (P trend =0.006). HIV post-exposure prophylaxis was prescribed for 64.5% (80/124) of males and 12.5% (48/384) of females. Among victims, 69.4% (358/516) were tested for HIV and no one tested positive, while 71.9% (371/516) were tested for syphilis, with 1.6% (6/371) positive. Gonorrhoea and chlamydia were tested at the oropharynx (44.8% [231/516] vs 28.7% [148/516]), genitals (83.7% [432/516] vs 92.4% [477/516]) and anorectum (35.3% [182/516] vs 35.3% [182/516]). Positivity for gonorrhoea and chlamydia were: 2.6% (6/231) vs 2.0% (3/148) at oropharynx, 1.4% (6/432) vs 2.9% (14/477) at genitals, and 5.5% (10/182) vs 7.1% (13/182) at anorectum. According to clinical records, 25.2% (130/516) of victims sought police involvement, and 71.7% (370/516) were offered counselling. Conclusions Sexual assault was an uncommon presentation at Melbourne Sexual Health Centre, with diverse circumstances surrounding assault; however, clinical documentation varied, indicating a need for a standard primary care protocol for clients presenting with acute sexual assault.

Reproductive health among women living with HIV attending Melbourne Sexual Health Centre for HIV care from February 2019 to February 2020.

BACKGROUND: Women living with HIV are a minority population with unique care needs. Rates of unintended pregnancy are higher among women living with HIV versus HIV negative women. However, uptake of contraception among women living with HIV including long-acting-reversible contraceptives (LARCs) remains low. This quality improvement project aimed to identify gaps in reproductive healthcare for women living with HIV attending Melbourne Sexual Health Centre (MSHC). METHODS: We performed a retrospective review of women living with HIV attending MSHC for HIV care February 2019-February 2020. Women aged over 45years were excluded. Primary outcomes included proportion using contraception, methods used and whether a sexual or reproductive health history had been taken in the past year. RESULTS: A total of 100 women were included, predominantly born overseas (Asia, 38%; sub-Saharan Africa, 34%). Of these, 5% were pregnant, 16% were trying to conceive and 1% were undergoing elective oocyte preservation. Of the remaining 74 women, 48.6% were using any form of contraception, including 17.6% women using less-effective methods (withdrawal and condoms), 6.8% using the combined oral contraceptive pill, 18.9% using LARCs and 5.4% using permanent methods. Sexual activity status was documented for 61% women, 1% declined to answer and not documented for 38% women. CONCLUSIONS: Rate of contraceptive use in this study was lower than previously reported among women living with HIV in Australia; however, our findings suggest contraceptive methods may be changing in light of undetectable equals untransmittable and increased fertility desires. Discussions regarding sexual activity and reproductive health were limited. Mechanisms to increase clinician-patient discourse regarding these important issues should be explored.

Prevotella and Gardnerella Are Associated With Treatment Failure Following First-line Antibiotics for Bacterial Vaginosis.

BACKGROUND: Bacterial vaginosis (BV) is a common vaginal dysbiosis that often recurs following first-line antibiotics. We investigated if vaginal microbiota composition was associated with BV recurrence. METHODS: We analyzed samples and data from 121 women who participated in 3 published trials evaluating novel interventions for improving BV cure, including concurrent antibiotic treatment of regular sexual partners (RSPs). Women diagnosed with BV received first-line antibiotics and self-collected vaginal swabs pretreatment and the day after finishing antibiotics (immediately posttreatment). 16S rRNA gene sequencing was performed on vaginal samples. Logistic regression explored associations between BV recurrence and features of the vaginal microbiota pre- and posttreatment. RESULTS: Sixteen women (13% [95% confidence interval {CI}, 8%-21%]) experienced BV recurrence within 1 month of treatment. Women with an untreated RSP were more likely to experience recurrence than women with no RSP (P = .008) or an RSP who received treatment (P = .011). A higher abundance of Prevotella pretreatment (adjusted odds ratio [AOR], 1.35 [95% CI, 1.05-1.91]) and Gardnerella immediately posttreatment (AOR, 1.23 [95% CI, 1.03-1.49]) were associated with increased odds of BV recurrence. CONCLUSIONS: Having specific Prevotella spp prior to recommended treatment and persistence of Gardnerella immediately posttreatment may contribute to the high rates of BV recurrence. Interventions that target these taxa are likely required to achieve sustained BV cure.

Changes in the Syphilis Rapid Plasma Reagin Titer Between Diagnosis and Treatment.

BACKGROUND: We compared the rapid plasma reagin (RPR) titer on the day of initial presentation with that on the day of syphilis treatment to inform clinical practice as to whether a repeated RPR test should be recommended. METHODS: We undertook a retrospective study between 1 March 2011 and 31 December 2020 at the Melbourne Sexual Health Centre in Australia among individuals who underwent syphilis serology on the day of initial presentation and the day of treatment, if the latter were within 14 days after initial presentation. We calculated the percentage of individuals with a ≥4-fold change in RPR titer, stratified by the time between initial presentation and treatment and by syphilis stage. RESULTS: Among the 766 included syphilis cases, the median duration between initial presentation and treatment was 6 days (interquartile range, 5-7 days). Of these cases, 14.8% (n = 113) had a ≥4-fold increase or decrease during this interval. The number of cases with a ≥4-fold increase or decrease in RPR titer increased with increasing time between initial presentation and treatment, from 5.7% (n = 6) 1-3 days after initial presentation to 26.2% (n = 27) at 10-14 days (Ptrend < .001). There was no significant difference in the number of cases with a ≥4-fold increase or decrease in RPR titer between syphilis stages (P = .66). CONCLUSIONS: Our data support the recommendation of repeating the RPR titer if the day of initial presentation and the day of treatment are different, even when treatment is within a few days after initial presentation.

gyrA Mutations in Mycoplasma genitalium and Their Contribution to Moxifloxacin Failure: Time for the Next Generation of Resistance-Guided Therapy.

BACKGROUND: Although single nucleotide polymorphisms (SNPs) in Mycoplasma genitalium parC contribute to fluoroquinolone treatment failure, data are limited for the homologous gene, gyrA. This study investigated the prevalence of gyrA SNPs and their contribution to fluoroquinolone failure. METHODS: Samples from 411 patients (male and female) undergoing treatment for M. genitalium infection (Melbourne Sexual Health Centre, March 2019-February 2020) were analyzed by Sanger sequencing (gyrA and parC). For patients treated with moxifloxacin (n = 194), the association between SNPs and microbiologic treatment outcome was analyzed. RESULTS: The most common parC SNP was G248T/S83I (21.1% of samples), followed by D87N (2.3%). The most common gyrA SNP was G285A/M95I (7.1%). Dual parC/gyrA SNPs were found in 8.6% of cases. One third of infections harboring parC G248T/S83I SNP had a concurrent SNP in gyrA conferring M95I. SNPs in gyrA cooccurred with parC S83I variations. Treatment failure was higher in patients with parC S83I/gyrA dual SNPs when compared with infections with single S83I SNP alone from analysis of (1) 194 cases in this study (81.2% vs 45.8%, P = .047), and (2) pooled analysis of a larger population of 535 cases (80.6% vs 43.2%; P = .0027), indicating a strong additive effect. CONCLUSIONS: Compared with parC S83I SNP alone, M. genitalium infections with dual mutations affecting parC/gyrA had twice the likelihood of failing moxifloxacin. Although antimicrobial resistance varies by region globally, these data indicate that gyrA should be considered as a target for future resistance assays in Australasia. We propose a strategy for the next generation of resistance-guided therapy incorporating parC and gyrA testing.

Cost-effectiveness of testing for Mycoplasma genitalium among men who have sex with men in Australia.

OBJECTIVES: Mycoplasma genitalium (MG) disproportionately affects men who have sex with men (MSM). We determined the cost-effectiveness of different testing strategies for MG in MSM, taking a healthcare provider perspective. METHODS: We used inputs from a dynamic transmission model of MG among MSM living in Australia in a decision tree model to evaluate the impact of four testing scenarios on MG incidence: (1) no one tested; (2) symptomatic MSM; (3) symptomatic and high-risk asymptomatic MSM; (4) all MSM. We calculated the incremental cost-effectiveness ratios (ICERs) using a willingness-to-pay threshold of $A30 000 per quality-adjusted life year (QALY) gained. We explored the impact of adding an antimicrobial resistance (AMR) tax (ie, additional cost per antibiotic consumed) to identify the threshold, whereby any testing for MG is no longer cost-effective. RESULTS: Testing only symptomatic MSM is the most cost-effective (ICER $3677 per QALY gained) approach. Offering testing to all MSM is dominated (ie, higher costs and lower QALYs gained compared with other strategies). When the AMR tax per antibiotic given was above $150, any testing for MG was no longer cost-effective. CONCLUSION: Testing only symptomatic MSM is the most cost-effective option, even when the potential costs associated with AMR are accounted for (up to $150 additional cost per antibiotic given). For pathogens like MG, where there are anticipated future costs related to AMR, we recommend models that test the impact of incorporating an AMR tax as they can change the results and conclusions of cost-effectiveness studies.

Factors Associated With Consenting to Receive an Automated Email Summary After a Sexual Health Clinic Visit.

BACKGROUND: Electronic health records allow for inexpensive communication with patients. In March 2021, the Melbourne Sexual Health Centre implemented an automated email summary ("Sexual Health Automated Visit Email" [SHAVE]) of a client's visit. This study evaluates the proportion of attendees at a sexual health service who opted in or out of SHAVE. METHODS: This study was conducted at the Melbourne Sexual Health Centre in Australia between March 2021 and June 2022. Univariable and multivariable logistic regression analyses were used to examine the client characteristics associated with consenting to SHAVE. RESULTS: There were 18,528 clients (men, 12,700; women, 5828) included in the final analysis and 55.2% (n = 10,233) consented to receiving SHAVE. Comparing with those who did not have a new sexually transmitted infection diagnosis, clients with a new diagnosis of a sexually transmitted infection, but not HIV, had lower odds of consenting to receiving SHAVE (chlamydia: adjusted odds ratio [aOR], 0.64 [95% confidence interval {CI}, 0.57-0.72]; gonorrhea: aOR, 0.71 [95% CI, 0.62-0.82]; syphilis: aOR, 0.75 [95% CI, 0.59-0.96]). Men had lower odds of consenting when compared with women (men who have sex with women only: aOR, 0.77 [95% CI, 0.71-0.84]; men who have sex with men: aOR, 0.68 [95% CI, 0.62-0.75]). Comparing with those born in Australia or Oceania, clients born in Europe had lower odds of consenting (aOR, 0.81; 95% CI, 0.70-0.94), whereas those born in Latin America or Caribbean had higher odds of consenting (aOR, 1.25; 95% CI, 1.04-1.51). CONCLUSIONS: Email summaries may serve as a valuable strategy to improve health communication and record keeping for clients. Understanding the client characteristics associated with consenting SHAVE will allow for the implementation of strategies to better communicate with clients.

Quantitation of Mycoplasma genitalium using droplet digital PCR.

Mycoplasma genitalium is a sexually transmitted infection with increasing concerns around antimicrobial resistance. Droplet digital PCR (ddPCR) is a rapid quantification method with high precision that may be useful for absolute quantitation of bacteria in samples. This study aimed to develop a ddPCR assay for the quantification of M. genitalium. ddPCR targeting the gene mgpB was established and analysed using the QX100 ddPCR system. The assay was evaluated against quantitated DNA standards, and then in comparison to an established quantitative PCR performed on the Lightcycler 480 II. DNA template of increasing complexity was used, including synthetic double stranded DNA, DNA extracts from laboratory-cultured M. genitalium strains (n = 17) and DNA from M. genitalium-positive clinical samples (n = 21). There was a strong correlation between ddPCR concentration estimates and measured DNA standards (r2 = 0.997), and between ddPCR and qPCR quantitation for different templates (r2 ranging from 0.953 to 0.997). ddPCR reliably detected template in a range from <10 copies per reaction to >104 copies per reaction and demonstrated linearity over dilution series. Concentration estimates by ddPCR were reproducibly less than those determine by qPCR. ddPCR demonstrated precise and reproducible quantitation of M. genitalium with a variety of templates.

Comparison of Seegene AnyPlexTM II STI-7e with standard-of-care diagnostic methods for the detection of Mycoplasma genitalium, Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis.

The AnyPlexTM II STI-7e panel assay (Seegene) detects seven sexually transmitted organisms (Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, M. hominis, Ureaplasma urealyticum, U. parvum, and Trichomonas vaginalis). This study compared the performance of AnyPlexTM II STI-7e with standard-of-care diagnostic methods. Samples (cervical or vaginal swabs, or urine) from 1330 women were tested on standard-of-care assays; 83/1318 (6.3%) tested positive for M. genitalium (ResistancePlus® MG), 99/1317 (7.5%) positive for C. trachomatis and 11/1316 (0.8%) positive for N. gonorrhoeae (Hologic® Aptima Combo 2®), and 6/689 (0.9%) positive for T. vaginalis (wet mount microscopy). AnyPlexTM II STI-7e had good agreement for the detection of M. genitalium [Cohen's kappa of 0.80, 95% confidence intervals (CI) 0.74-0.87] and C. trachomatis (kappa of 0.87, 95% CI 0.82-0.92), with positive and negative % agreement >96% for both infections. There was lower agreement for the detection of N. gonorrhoeae (kappa of 0.37, 95%CI 0.19-0.55) and T. vaginalis (kappa of 0.521, 95%CI 0.25-0.80). In summary, the test performed well in this comparison for M. genitalium and C. trachomatis detection, but results were less conclusive for N. gonorrhoeae and T. vaginalis due to low prevalence in the population.

Sexual activities and condom use among heterosexual men and women engaged in mixed-gender group sex events in Melbourne, Australia.

BACKGROUND: Few studies investigate group sex among heterosexuals. The aim of this study was to provide an exploration of characteristics and practices among heterosexual men and women who engage in group sex. METHOD: We conducted a cross-sectional survey between May 2019 and March 2020 among heterosexual men and women attending a sexual health clinic in Melbourne, Australia. Participants were asked whether they had participated in group sex (sex involving more than two participants) in the past 3months, the size of the most recent event, sexual activities in which they engaged, and condom use. RESULTS: Of 3277 heterosexuals surveyed (1509 women and 1768 men), the mean age was 29.9years (s.d. 8.8) and more than half (56.0%, n =1834) were born outside Australia. One in 20 participants (5.4%) had engaged in group sex in the past 3months with the number of events ranging 1-10times. Kissing was the most common activity in group sex, and women were significantly more likely to kiss a same-sex partner than men. Overall, of 165 participants who engaged in vaginal sex, 57 (34.5%) reported always using condoms and changing condoms between consecutive partners. Of the 100 men and women who had condomless vaginal sex, 79 (79.0%) received or performed fellatio after condomless vaginal sex. CONCLUSION: About two-thirds of heterosexuals who engaged in group sex neither used condoms nor changed condoms between partners in the most recent group sex event. Safe sex messages on changing condoms between partners and between sexual activities should be reinforced for sexually transmitted infections prevention.

Trends and associated factors in HIV testing among heterosexual men and women in Melbourne, Australia, 2011-2020.

BACKGROUND: Despite the increase in the proportion of HIV notifications attributed to heterosexuals in Australia, little is known about their HIV testing behaviours. We investigated the trends and factors associated with HIV testing behaviours among heterosexuals. METHODS: We analysed the trend and proportion of heterosexuals attending the centre for the first time between 2011 and 2020, who had ever tested and tested for HIV in the past 12months and the median number of months since their last HIV test. We identified factors associated with HIV testing behaviours using univariable and multivariable logistic regressions. RESULTS: Of the 78652 heterosexuals included, 53.1% were men and 46.9% were women. Overall, the proportion of heterosexuals who had ever tested for HIV was 40.8%, with a declining testing trend from 40.2% in 2011 to 36.5% in 2020 (P trend <0.001). Overall, the proportion of heterosexuals tested for HIV in the past 12months was 15.7%, with no significant change from 15.3% in 2011 to 14.7% in 2020 (P trend =0.489). The median number of months since the last HIV test decreased from 18.0 (IQR 6.9-37.3) in 2011 to 15.0 (IQR 6.4-32.5) in 2020 (P trend <0.001). Individuals who had condomless sex with casual partners (aOR 0.92, 95% CI 0.88-0.96) and who were diagnosed with a sexually transmitted infection (aOR 0.88, 95% CI 0.84-0.93) were less likely to have ever tested for HIV. CONCLUSIONS: HIV testing was low among heterosexuals, and individuals who engaged in condomless sex and had another sexually transmitted infection were less likely to be tested. To reduce HIV transmission, strategies to improve HIV testing among heterosexuals are needed.

Mpox knowledge, vaccination and intention to reduce sexual risk practices among men who have sex with men and transgender people in response to the 2022 mpox outbreak: a cross-sectional study in Victoria, Australia.

BACKGROUND: The first mpox case was reported in May 2022 in Australia. Most cases have been diagnosed in men who have sex with men (MSM). This study aimed to examine community understanding of mpox, attitudes towards vaccination, and potential changes in sexual practices surrounding the mpox outbreak among MSM and transgender people in Victoria, Australia. METHODS: Participants were recruited from sexual health clinics and communities in Victoria, Australia, in August-October 2022. Participants were asked about their understanding and knowledge of mpox, vaccination uptake and intentions to change sexual practices. Univariable and multivariable logistic regression was performed to examine the factors associated with mpox vaccine uptake. RESULTS: Most participants (97.8%, 525/537) had heard about mpox and 10.5% (55/525) knew someone who had had mpox. Of the 12 mpox knowledge questions, the median score of correct answers was 10 (IQR=8-11) out of a maximum of 12. More than a third (36.6%, 191/522) had been vaccinated against mpox. MSM who had a good knowledge of mpox had the highest odds of receiving mpox vaccine compared with those who had poor knowledge (aOR=4.05; 95% CI: 1.54-10.61). To prevent mpox, half reported they would reduce having sex with casual partners, stop having chemsex (used drugs for the purpose of sex), stop attending sex-on-premises-venues, and stop having group sex. A quarter reported they would increase condom use for anal sex. CONCLUSIONS: One-third of high-risk participants and a substantial proportion of participants intended to reduce or stop certain practices, which may explain the large reduction in mpox cases.

Combination Therapy for Mycoplasma genitalium, and New Insights Into the Utility of parC Mutant Detection to Improve Cure.

BACKGROUND: Mycoplasma genitalium (MG) infection is challenging to cure because of rising antimicrobial resistance and limited treatment options. METHODS: This was a prospective evaluation of the efficacy and tolerability of resistance-guided combination antimicrobial therapy for MG treatment at Melbourne Sexual Health Centre (August 2019-December 2020). All patients received 7 days of doxycycline before combination therapy based on the macrolide-resistant profile. Macrolide-susceptible infections received combination doxycycline + azithromycin (1 g, day 1; 500 mg, days 2-4) and macrolide-resistant infections combination doxycycline + moxifloxacin (400 mg daily for 7 days). Adherence and adverse effects were recorded at test-of-cure, recommended 14-28 days after antimicrobial completion. Sequencing was performed to determine the prevalence of single nucleotide polymorphisms (SNPs) in the parC gene and their association with moxifloxacin treatment outcomes in macrolide-resistant infections. RESULTS: Of 100 patients with macrolide-susceptible MG treated with doxycycline + azithromycin, 93 were cured (93.0%; 95% confidence interval [CI], 86.1-97.1). Of 247 patients with macrolide-resistant MG receiving doxycycline + moxifloxacin, 210 were cured (85.0%; 95% CI, 80.0-89.2). parC sequencing was available for 164 (66%) macrolide-resistant infections; 29% had SNPs at parC S83 or D87 (23% S83I). The absence of SNPs at parC S83/D87 was associated with 98.3% cure (95% CI, 93.9-99.8) following doxycycline + moxifloxacin. The presence of the parC S83I-SNP was associated with failure in 62.5% (95% CI, 45.8-77.3). Side effects were common (40%-46%) and predominantly mild and gastrointestinal. CONCLUSIONS: Combination doxycycline + azithromycin achieved high cure for macrolide-susceptible infections. However, in the context of a high prevalence of the parC S83I mutation (23%) in macrolide-resistant infections, doxycycline + moxifloxacin cured only 85%. Infections that were wild-type for S83/D87 experienced high cure following doxycycline + moxifloxacin, supporting the use of a parC-resistance/susceptibility testing strategy in clinical care.

parC Variants in Mycoplasma genitalium: Trends over Time and Association with Moxifloxacin Failure.

Prevalence, trends, and treatment outcome estimates were generated for parC variants in macrolide-resistant Mycoplasma genitalium. Among 539 cases, the most common amino acid change was S83I, which increased from 13% in 2012 to 2013, to 23% in 2019 to 2020 (Ptrend = 0.046). From 381 moxifloxacin treatments, failure occurred in 58.7% (95% confidence interval [CI], 46.7 to 69.9) of cases with S83I. Other changes affecting S83 or D87 were uncommon and minor contributors to failure. The absence of S83I was highly predictive of moxifloxacin cure (96.4%; 95% CI, 93.7 to 98.2), highlighting diagnostic potential.

Impact of 16S rRNA Single Nucleotide Polymorphisms on Mycoplasma genitalium Organism Load with Doxycycline Treatment.

Doxycycline targets the 16S rRNA and is widely used for the treatment of sexually transmitted infections. While it is not highly effective at eradicating Mycoplasma genitalium infections, it can reduce organism load. The aim of this study was to investigate the association between single nucleotide polymorphisms (SNPs) in the 16S rRNA gene of M. genitalium and change in organism load. M. genitalium samples were collected from 56 men prior to commencing doxycycline and at a median of 13 of 14 doses. These were sequenced for the 16S rRNA, and the association between 16S rRNA SNPs and change in organism load was determined. 16S rRNA sequences were available for 52/56 (92.9%) M. genitalium-infected men, of which 20 (38.5%) had an undetectable load, 26 (50.0%) had a decrease in M. genitalium load (median change of 105-fold), and 6 (11.5%) had an increase in load (median change of 5-fold). The most common SNPs identified were A742G (10/52 [19.2%]), GG960-961TT/C (7/52 [13.5%]), and C1435T (28/52 [53.8%]) (M. genitalium numbering). None were associated with a change in organism load (P = 0.76, 0.16, and 0.98, respectively). Using pooled published data from 28 isolates, no clear relationship between the SNPs and doxycycline MIC was identified. In conclusion, the low efficacy of doxycycline against M. genitalium does not appear to be due to variation in the 16S rRNA gene.

Novel probe-based melting curve assays for the characterization of fluoroquinolone resistance in Mycoplasma genitalium.

BACKGROUND: Mycoplasma genitalium infection is a sexually transmitted infection that has rapidly become resistant to mainstay treatments. While individualized treatment approaches have been recommended and adopted for macrolides, individualized therapy for fluoroquinolones has not yet been explored, due to a lack of commercial molecular assays and a lack of confidence in specific mutations associated with resistance. In another recent study, we defined a clear role and diagnostic utility in focusing on the absence of resistance mutations to inform microbial cure with fluoroquinolone antimicrobials. METHODS: We developed two proof-of-concept molecular tests that focus on detection of M. genitalium and characterization of WT parC sequences that are strongly linked to fluoroquinolone susceptibility. RESULTS: We screened a total of 227 M. genitalium-positive samples using novel molecular beacon and dual hybridization probe assays. These assays were able to detect M. genitalium and characterize fluoroquinolone susceptibility in 143/227 (63%) samples, based on clear differences in melting peak temperatures. The results of these molecular assays were in 100% agreement with 'gold standard' Sanger sequencing. Additionally, WT parC sequences were readily distinguished from M. genitalium samples harbouring parC mutations of known or suspected clinical significance. The ability of the assays to successfully characterize fluoroquinolone susceptibility and resistance was reduced in low M. genitalium load samples. CONCLUSIONS: These proof-of-concept assays have considerable potential to improve individualized treatment approaches and rationalize tests of cure for M. genitalium infection. The ability to initiate individualized treatment in up to two-thirds of cases will enhance antimicrobial stewardship for this challenging pathogen.